[Python-ideas] Is this PEP-able? "with" statement inside genexps / list comprehensions

[Serhiy Storchaka]

31.07.18 00:26, Oscar Benjamin пише:
> On 30 July 2018 at 20:15, Rudy Matela <rudy at matela.com.br> wrote:
> Yielding from a with block should be discouraged rather than given
> special syntax. There is essentially a contradiction between the
> meaning/purpose of yield (suspend indefinitely) and with (definitely
> call __exit__).
> 
> If I partially iterate over g as in
> 
>      for line in g:
>          break
> 
> then at this point g is suspended and f.__exit__ has not been called,
> so the file is not closed. I may choose to iterate over g later or
> not, so it has to remain in suspension just in case. In practice if
> you do this in CPython then f.__exit__ will *probably* be invoked
> indirectly by g.__del__ if/when the gc collects g. This defeats the
> main point of using with-open though which is to avoid depending on
> the gc for closing files.

Concur with Oscar.